Hydraulic angling bulldozer



I5 Sheets-Sheet 1 Filed Dec. 24, 1951 RlGEN S- PERK W S.

I INVENTOR, y 4w @ci. 16, 1956 o. s. PERKINS HYDRAULIC ANGLING BULLDOZER Filed D90. 24. 1951 3 Sheets-Sheet 2 g .P m 8 m M. H m s A W /1 z w W M M f A R f o i Oct. 16, 1956 o. s. PERKINS 2,766,536

HYDRAULIC ANGLING BULLDOZER Filed D60. 24. 1951 5 Sheets-Sheet 3 ORICxEN s. PERK wsQ FQEL INVENTOR,

HYDRAULIC ANGLING BULLDOZER Origen S. Perkins, Hales Corners, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis., 21 corporation of Delaware Application December 24, 1951, Serial No. 263,041

2 Claims. (Ci. 37-444) My invention relates to new and useful improvements in tractor-mounted bulldozers, more particularly to an improved means for elfecting hydraulic angling, tilting, and/or tipping of the bulldozer blade.

In bulldozers of the type to which my invention is more particularly adapted, namely angling bulldozers, a U-shaped frame surrounds the front end of a tractor, the ends of the two arms of the U being pivoted to the sides of the tractor, usually on or adjacent the rear axles thereof. The center of the base of the U is attached to the center of the rear of the blade by means of a pivot mounting which permits the blade to be angled in a normally horizontal plane, An adjustable side beam extends from the side of the U to each end of the blade. Moving the rear end of the beams into various selected positions on the U-frame effects angling of the blade in the horizontal plane. Tilting of the blade about a fore-and-aft axis is accomplished by providing a joint in one of the arms of the U-frame adjacent the rear end of the arm, so that vertical movement of the joint will swing that side of the U-frame and the adjacent end of the blade upwardly or downwardly to tilt the blade. Tipping of the blade about a transverse axis is accomplished by providing two such joints, one in each arm of the U- frame, so that raising or lowering both joints simultaneously will raise or lower both ends of the U-frame simultaneously and thereby tip the blade either forwardly or rearwardly as the case may be.

The principal objects of my invention are to provide an improved hydraulically controlled angling bulldozer, in which (1) The blade can be angled to cast dirt to one side without stopping the machine.

(2) The speed of angling is approximately the same for angling in either direction.

(3) The force applied to angle the blade is approximately the same in either direction of angling.

(4) The fluid flow and fluid storage requirements are a minimum and approximately the same for angling movement in either direction.

(5) Hydraulically controlled angling movement is independent of hydraulically controlled lift, tilt, or tipping motion of the blade, in order to provide maximum power for angling, without use of separate pumps, tanks, or main control valves for the four motions.

' (6) Hydraulic angling of the blade is accomplished simply and compactly by means directly connected between the U-frame and the blade and so arranged that there is no interference with full angling of the blade.

(7) Each end of the blade is effectively braced against tilting motion with respect to the U-frame in any angled position.

In addition to the objects above stated, I have worked out a number of novel and useful details which will be readily evident as the description progresses. My invention consists in the novel parts and in the combination and arrangement of which are defined in the appended claims, and of which three embodiments are exemplified 2,7653% Patented (lot. 16, 1956 in the accompanying drawings which are hereinafter particularly described and explained.

Throughout the description the same reference number is applied to the same member or to similar members. Referring to the accompanying drawings it will be seen that:

Figure l is a side elevation of a first embodiment of the improved angling type bulldozer, with the tractor indicated in outline only.

Figure 2 is a plan view of the angling bulldozer shown in Figure 1.

Figure 3 is a schematic diagram of the hydraulic circuit employed in a second embodiment of the improved angling bulldozer.

Figure 4 is a schematic diagram of the hydraulic circuit employed in a third embodiment of the improved angling bulldozer.

Referring now to Figures 1 and 2 we see that 11 and 12 represent a pair of transversely-spaced longitudinallyextending side arms of a U-shaped bulldozer-supporting frame 13, the front transverse portion 14 of which serves to mount the bulldozer blade unit 15 forwardly of a tractor (shown in dotted outline). The rear ends 16, 17 of side arms 11, 12 respectively are connected by means of ball-and-socket type universal joints 18, 19 to trunnion brackets 20, 21 which are adapted to be rigidly secured to the outside of the track frames of the tractor adjacent the rear axle of the tractor,

Blade unit 15 is a built-up structure consisting of a front moldboard 15a, a longitudinal digging edge 15!), and a back plate mounted on the back of the moldboard by means of longitudinal angle irons. These details of the blade unit structure are merely of one of a number of conventional types of construction and form no part of my invention.

Blade unit 15 is disposed transversely of the U-frame 13 in advance of the front portion 14 of the U-frame. It is mounted to be swung in a normally-horizontal plane about the axis of king pin 22 which extends vertically through the nose of the U-frame and through rearwardly projecting spaced lugs 23 on the back of the blade unit 15. Accordingly the blade unit 15 may be swung or angled in a normally horizontal plane into selected positions with respect to the longitudinal axis of the U- frame 13.

In order to brace the blade unit 15 against tilting movement about a horizontal axis with respect to the U-frame, in any given angled position, channel retaining beams 24, 25, popularly known as landsides, are provided between the side arms 11, 12 respectively and the ends of the blade unit 15. The rear end of each landside slides between rails 26 which are welded to the top and bottom of each side arm. The landsides are of such length that, in any angled position, their flanges engage a substantial portion of the length of the side arms 11, 12, and thereby are braced against any vertical reaction from the ends of the blade unit to which the landsides are attached. The forward ends of the landsides 24, 25 are pivotally connected by vertical pins 27 to the back of the blade unit 15, one adjacent each end thereof. This permits each landside to pivot about the vertical axis of its pin 27 as the blade unit 15 is moved into any angled position.

The blade unit 15 and its supporting U-frame 13 are raised and lowered about the transverse axis through universal joints 18, 19 by conventional cylinder-piston assemblies 28, 29 which are mounted at one end by universal connections 30, 31 on bracket 32 on the forward portion of the tractor, and are connected at their other end by universal connections 33, 34 to the forward portion 14 of the U-frame 13. Pressure fluid to operate the cylinder-piston assemblies 28, 29 is supplied, as

hereinafter described, from a conventional hydraulic unit 35 mounted at the front of the tractor. The corresponding ends of cylinder-piston assemblies 28, 29 are interconnected in order to provide an equalized effective central support for the U-frame in all its positions.

The blade unit 15 is tilted about an oblique fore-andaft and tipped fore-and-aft about its transverse axis by the following described mechanism. Intermediate the ends of each of the side arms 11, 12 there is a transverse pivot joint 36 which permits rearward and forward segments 37 and 38 respectively of the side arm to pivot relative to each other about a transverse axis. Such relative pivoting of segments 37 and 38 about pivot 36 is eifected by extensible and retractable means, such as a double-acting cylinderrpiston assembly 39, which is pivotally connected at one end to an upstanding bracket 49 on the rear segment 37 and at the other end to lugs 41 on forward segment 38 of the side arm. Each cylinder-piston assembly 39 is actuated by pressure fluid from hydraulic unit 35, as hereinafter described. When one of the cylinder-piston assemblies 39 is actuated, or both of such assemblies are actuated in opposite directions, the U-frame is distorted so that the blade unit will tilt about a fore-and-aft axis, the axis running in the first case obliquely through the center of the blade unit and the rear end of the side arm that is not so distorted and running in the latter case centrally through the tractor. When both of the cylinder-piston assemblies 3? are actuated in the same direction, the rear end of the U-frame is raised or lowered, and the blade unit is thereby tipped for or aft as the case may be.

The blade unit 15 is angled about a normally-vertical axis through king pin 22 by cylinder-piston assemblies 42, 43, which are mounted at one end by normally-vertical pivot connections 44, 45 respectively on the front portion 14 of U-frame 13 intermediate the king pin 22 and the side arms 11 and 12, and are pivotally connected at their other end to the respective ends of the blade by the normally vertical pins 27 aforementioned. The rear ends of these cylinder-piston assemblies are mounted in such a position on the front portion 14 of the U-frame, that they lie approximately parallel to the back of the blade unit in a jackknifed position in or nearly in toggle position when the cylinder-piston assembly in question is fully retracted and the end of the blade unit adjacent the retracting cylinder is angled into its fully rearwardly retracted position against the front portion 14 of the U-frame. By proper selection of the rear pivots of cylinder-piston assemblies 42, 43 the assemblies can thus be jackknifed into compact relation with the blade unit and the front portion 14 of the U-frame when the ad jacent end of the blade unit is fully retracted.

Pressure fluid to operate the angling cylinder-piston assemblies 42, 43 is supplied from hydraulicunit 3521s hereinafter described.

Hydraulic unit 35 is mounted at the front endof the tractor engine, and is driven by the tractor. It comprises an hydraulic storage tank or tanks, an hydraulic pump, a control valve for the control of the flow to and from the pump, and various incidental conduits, relief valves and one-way valves. Since this hydraulic unit is Well known in the art (see U. S. Patent No. 2 ,58l .430, issued January 8, 1952, to G. W. Mork et al.) and forms no part of my present invention, it is merely shown schematically in the figures. Suffice to say that the hydraulic unit has two fluid ports which are connected (as;

hereinafter described) to the cylinder-piston assemblies which the hydraulic unit controls. The plunger of the control valve of the hydraulic unit has four positions to control the flow of fluid to and from the pump in four cases as follows:

(1) Raise po sitian.Fluid under pressure is de-. livered by the pump through one of the ports (called the raise port) of the hydraulic unit to the corresponding raise end of the cylinders; return fluid from the lower end of the cylinders through the other port (called the lower port) of the hydraulic unit into the pump in livered by the. pump through the lower port of; the

hydraulic unit to the lower end of the cylinders; return fluid passing from the raise end of the cylinders through the raise port of the hydraulic unit into the pump intake.

(4) Float p0siti0n.Raise and lower ports of the hydraulic unit and hence the raise and lower ends of the cylinders intercommunicate and communicate, with flow permitted in either direction through the control valve and tank of the hydraulic unit. the piston is free to float in its cylinder.

Referring to Figures 1 and 2, it is seen that the main controlvalve 46 of the hydraulic unit 35 is mounted at the top of the hydraulic unit, both being shown schematically. Mounted above control valve 46 is a conventional two-position selector valve 47, the details of which.

are. not shown because they are well known in the art. In its first position the selector valve 47 directs fluid from the raise and lower ports (not shown) of the hydraulic unit to the conduits 48R, 48L which supply. fluid to the raise ends 49R and the lower ends 49L of the lift cylinders 28, 29. In the second position ofselector valve 47, fluid is directed from the raise" andlower ports of the hydraulic unit to the conduits 50. and 51 respectively which lead to the angling cylinderpiston assemblies 42, 43 as hereinafter described.

In the first position of the selector valve 47, flow to. conduits 5t and 51 is blocked oil; and in the second,

position of selector valve 47, flow from the hydraulic unit to conduits 48R and 48L is blocked off.

Pressure fluid to the tilt cylinder piston assemblies 39. is supplied from the hydraulic unit by conduits 52R and 52L which run from conduits 48R and 48L respectively to a conventional three-position reversing valve 53 (de-. tails not shown) and thence to the raise and lower ends.

54R and 541. of cylinder-piston assemblies 39, which are interconnected in parallel by conduits 55R and SSL. A second three-position reversing valve 56 is placed in series same direction as the left-hand cylinder 39 to produce tipping of the blade, or to actuate right-hand cylinder 39. simultaneously with but in the opposite direction of left hand cylinder 39 to produce tilting of the blade, or to block otf right-hand cylinder 39 so that only left-hand cylinder- 39 can be actuated fortilting only of the blade.

The selector and reversing valves above described are.

conventional and well known in the art, and therefore are not shown in detail.

Pressure fluid to the angling cylinder-piston assemblies 42 and 43 is supplied from the hydraulic unit 35, through selector valve 47 (in its second position), through conduits 50 and 51 (which are connected by the selector valve respectively to the raise and lower ports of the hydraulic unit), to conduits 57 and 58 which interconnect the ends of'the cylinder-piston assemblies 42 and 43. Conduit 57 interconnects rear port 59 of cylinder 42 Hence with front port 62 of cylinder 43. Conduit 58 interconnects rear port 61 of cylinder 43 with front port 60 of cylinder 42. Ports 59 and 62 serve as intake ports when the blade unit is being angled counterclockwise (see Figure 2), and serve as exhaust ports when the blade unit is being angled clockwise. Ports 60 and 61 serve as intake ports when the blade unit is angled clockwise. and serve as exhaust ports when the blade is angled counterclockwise. Thus it will be seen that cylinders 42 and 43 are interconnected in parallel in arch a manner that, for angling in either direction, the intake ports of said cylinders are interconnected with each other and the exhaust ports of said cylinders are interconnected with each other, each interconnected pair of ports having an individual fluid connection with the hydraulic unit for the supply or displacement of fluid to or from the cylinders.

The parallel interconnection between the cylinders .2 and 43 is further characterized by the fact that the expansion chamber 63 of each cylinder is interconnected in parallel with the retraction chamber 64 of the other cylinder, so that the speed of an ling is the same in one direction of angling as the speed in the other direction.

Turning now to Figure 3 it will be seen that this is a schematic representation of a modification (representing a second embodiment) of the hydraulic circuit shown in Figure 2. In this second embodiment, a second selector valve 65 is employed to direct pressure fluid at will from selector valve 47 (second position) either to the angling cylinder piston assemblies 42, 4 3 or to the single tilting cylinder 39. This circuit gives independent control of each of the lift, angling and tilting functions, so that the entire power of the hydraulic unit is available for any single desired function.

Turning to Figure 4 it is seen that this is a schematic representation of a modification (representing a third embodiment) of the hydraulic circuit shown in Figure 2. in this third embodiment. the angling cylinders 42, 43, instead of the tilt cylinders 39, are placed in parallel with the lift cylinders 28, 29, and the tilt cylinders 39 are fed independently from the selector valve 47. This arrangement permits tilting (or tipping) independently of the lifting or angling motions. Furthermore since the angling and lift cylinders are in parallel, it is possible. when the main control valve is in hold position and flow of fluid through the selector valve is blocked, to use the potential energy of the weight of the blade unit, which sets up a fluid pressure in the lift cylinders 28, 29, to actuate angling cylinders 42, 43 and thereby angle the blade unit in either direction (by appropriate setting of reversing valve 66). By use of this method of angling, it is possible to angle the blade at a slower rate of speed than in the first embodiment where angling was power actuated, and finer adjustment of the blade unit is therefore possible.

Having now described and illustrated three forms of my invention, it is to be understood that the invention is not to be limited to the specific form or arrangement of parts herein described and shown.

I claim:

1. In a bulldozer, the combination of: a supporting frame; a blade unit disposed transversely ahead of said supporting frame; means pivotally mounting the blade unit intermediate its ends on the frame for angling movement in a normally horizontal plane; a pair of hydraulic rams connecting portions of the blade unit, on either side of said mounting, to the supporting frame and adapted to actuate and lock said blade unit in any selected angled position and having pivotal connections to the supporting frame and to the blade-unit so positioned that, when the blade-unit is in fully-angled position, the ram adjacent the retracted portion of the blade-unit is jackknifed into a position approximately parallel to the back r of the blade.

2. in a bulldozer, for attachment to a tractor, the combination of: a transverse blade unit; a frame connected with the blade unit and adapted to be connected with the tractor, whereby the blade unit and the frame may be raidsed and lowered as a unit and the blade unit may be angled with respect to the frame about a normally vertical central axis; a double-acting hydraulic lift cylinder-piston assembly operatively connected with the frame and adapted to be carried by the tractor to power raise and power lower the frame and blade unit; a doubleacting hydraulic angling cylinder-piston assembly pivotally connected between the blade unit and the frame for angling the blade unit with respect to the frame; a source of fluid under pressure; fluid connections between said source and said lift cylinder-piston assembly; valve control means associated with said fluid connections to provide or block at will communication in a selected direction between said source and said lift cylinder-piston assembly; and reversible fluid connections, independent of said control means, interconnecting said assemblies, whereby, when the control means blocks communication from said source to the lift cylinder-piston assembly, the angling cylinder-piston assembly will be actuated by fluid under pressure of the weight of the blade unit passing directly from and displaced by the lift cylinder-piston assembly and, when the control means provides communication from said source to said lift cylinder-piston assembly to power lower and power raise the blade, said lift cylinder-piston assembly and said angling cylinder-piston assembly are actuable simultaneously to control elevation of and to angle the blade.

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